| Message ID | 1399439776-18535-1-git-send-email-bjorn.andersson@sonymobile.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, May 6, 2014 at 10:16 PM, Bjorn Andersson <bjorn.andersson@sonymobile.com> wrote: [...] > +static int fdt_overrides_atag_mem(void *fdt) > +{ > + const char *memory; > + int len = 0; > + > + memory = getprop(fdt, "/memory", "reg", &len); > + if (memory) { > + while (len--) { > + if (*memory != '\0') Sorry, this is of course supposed to be: if (*memory++ != '\0') > + return 1; > + } > + } > + > + return 0; > +} Regards, Bjorn
On Tue, May 06, 2014 at 10:16:16PM -0700, Bjorn Andersson wrote: > Support overriding ATAG_MEM, by specifying non-zero content of the /memory/reg > property in the appended DTB. This is needed to work around bootloaders passing > broken tags. This feels wrong. I think it's quite usual that the device tree specifies a non-0 /memory/reg property. I checked four more or less random dts files[1], and three of them have this property set with actual values. So I wouldn't be surprised if this patch results in more damage than it's worth. The optimal fix would be to make the bootloader do the right thing. And if you trust your dtb more than your bootloader, disable ARM_ATAG_DTB_COMPAT. Best regards Uwe [1] arch/arm/boot/dts/am335x-bone-common.dtsi arch/arm/boot/dts/exynos5440-sd5v1.dts arch/arm/boot/dts/imx6q-wandboard.dts arch/arm/boot/dts/tegra30-cardhu.dtsi > > Signed-off-by: Bjorn Andersson <bjorn.andersson@sonymobile.com> > --- > arch/arm/boot/compressed/atags_to_fdt.c | 18 +++++++++++++++++- > 1 file changed, 17 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/boot/compressed/atags_to_fdt.c b/arch/arm/boot/compressed/atags_to_fdt.c > index d1153c8..b534cd6 100644 > --- a/arch/arm/boot/compressed/atags_to_fdt.c > +++ b/arch/arm/boot/compressed/atags_to_fdt.c > @@ -95,6 +95,22 @@ static void merge_fdt_bootargs(void *fdt, const char *fdt_cmdline) > setprop_string(fdt, "/chosen", "bootargs", cmdline); > } > > +static int fdt_overrides_atag_mem(void *fdt) > +{ > + const char *memory; > + int len = 0; > + > + memory = getprop(fdt, "/memory", "reg", &len); > + if (memory) { > + while (len--) { > + if (*memory++ != '\0') [added fixup noted in follow-up-mail] > + return 1; > + } > + } > + > + return 0; > +} > + > /* > * Convert and fold provided ATAGs into the provided FDT. > * > @@ -180,7 +196,7 @@ int atags_to_fdt(void *atag_list, void *fdt, int total_space) > } > } > > - if (memcount) { > + if (memcount && !fdt_overrides_atag_mem(fdt)) { > setprop(fdt, "/memory", "reg", mem_reg_property, > 4 * memcount * memsize); > } > -- > 1.7.9.5 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >
On Wed, May 7, 2014 at 1:06 AM, Uwe Kleine-König <u.kleine-koenig@pengutronix.de> wrote: > On Tue, May 06, 2014 at 10:16:16PM -0700, Bjorn Andersson wrote: >> Support overriding ATAG_MEM, by specifying non-zero content of the /memory/reg >> property in the appended DTB. This is needed to work around bootloaders passing >> broken tags. > This feels wrong. I think it's quite usual that the device tree > specifies a non-0 /memory/reg property. I checked four more or less > random dts files[1], and three of them have this property set with > actual values. I thought u-boot did something like this, but after checking the code it seems that I was wrong. But if that's not the case then you're right; we have to continue to be bug-compatible with all those dtbs out there. > > So I wouldn't be surprised if this patch results in more damage than > it's worth. The optimal fix would be to make the bootloader do the right > thing. And if you trust your dtb more than your bootloader, disable > ARM_ATAG_DTB_COMPAT. I unfortunately have a boot loader passing information in ATAG_CMDLINE that I need, so I can't disable ARM_ATAG_DTB_COMPAT. My problem is that the boot loader on every shipped Qualcomm MSM8x60, MSM8960 and APQ8064 based device passes ATAG_MEM with the incorrect start address. There is no way to update the boot loader for these. For development I have a .init_meminfo in my board file patching the meminfo; this looks really bad so I'm hoping we can find some alternative solution. The proposed solution from some of the people working on this is to (post build) patch the zImage to inject code that corrects the ATAG_MEM before jumping to the kernel; but I am hoping we can find some sane way instead... Regards, Bjorn
Am 07.05.2014 17:29, schrieb Bjorn Andersson: > My problem is that the boot loader on every shipped Qualcomm MSM8x60, MSM8960 > and APQ8064 based device passes ATAG_MEM with the incorrect start address. There > is no way to update the boot loader for these. Chaining bootloaders comes to mind. This is being done on the Exynos5 based Chromebooks, for instance. Regards, Andreas
On Wed 2014-05-07 23:24:18, Andreas F?rber wrote: > Am 07.05.2014 17:29, schrieb Bjorn Andersson: > > My problem is that the boot loader on every shipped Qualcomm MSM8x60, MSM8960 > > and APQ8064 based device passes ATAG_MEM with the incorrect start address. There > > is no way to update the boot loader for these. > > Chaining bootloaders comes to mind. This is being done on the Exynos5 > based Chromebooks, for instance. You can easily start fixed u-boot from broken u-boot... But I'm not sure that's the way to go. Perhaps your localised/ugly hack in board init code is the way to go... Pavel
diff --git a/arch/arm/boot/compressed/atags_to_fdt.c b/arch/arm/boot/compressed/atags_to_fdt.c index d1153c8..b534cd6 100644 --- a/arch/arm/boot/compressed/atags_to_fdt.c +++ b/arch/arm/boot/compressed/atags_to_fdt.c @@ -95,6 +95,22 @@ static void merge_fdt_bootargs(void *fdt, const char *fdt_cmdline) setprop_string(fdt, "/chosen", "bootargs", cmdline); } +static int fdt_overrides_atag_mem(void *fdt) +{ + const char *memory; + int len = 0; + + memory = getprop(fdt, "/memory", "reg", &len); + if (memory) { + while (len--) { + if (*memory != '\0') + return 1; + } + } + + return 0; +} + /* * Convert and fold provided ATAGs into the provided FDT. * @@ -180,7 +196,7 @@ int atags_to_fdt(void *atag_list, void *fdt, int total_space) } } - if (memcount) { + if (memcount && !fdt_overrides_atag_mem(fdt)) { setprop(fdt, "/memory", "reg", mem_reg_property, 4 * memcount * memsize); }
Support overriding ATAG_MEM, by specifying non-zero content of the /memory/reg property in the appended DTB. This is needed to work around bootloaders passing broken tags. Signed-off-by: Bjorn Andersson <bjorn.andersson@sonymobile.com> --- arch/arm/boot/compressed/atags_to_fdt.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-)